Abstract: In a half-bridge self-exciting switching power supply, an over-voltage detector receives the power supply output and generates an over-voltage signal when the power supply output exceeds a preset limit. An over-voltage cut-off circuit is connected to a pulse-width-modulated controller and a driving unit of the switching power supply. The over-voltage cut-off circuit applies a pull-down voltage to the driving unit so as to inhibit self-exciting operation of first and second self-excited switching circuits of a half-bridge self-excited circuit, and disables the pulse-width-modulated controller upon reception of the over-voltage signal from the over-voltage detector. Therefore, when the pulse-width-modulated controller or the driving unit becomes defective, the switching power supply can be cut-off automatically in order to prevent damage to a load and to the other components of the switching power supply.

Abstract: An electrical appliance includes a conductive casing, a connector and a grounding device. The connector includes an insulator body mounted on the conductive casing, and a ground terminal disposed on the insulator body. The ground terminal has a connecting end that extends inwardly of the conductive casing. The grounding device includes a metal plate which has a first end mounted on the conductive casing, and a second end defining an engaging hole that engages the connecting end of the ground terminal.